Electrotype material and method of forming same



G. U. ROSE, JR-

ELECTROTYPE MATERIAL AND METHOD OF FORMING SAME.

APPLICATION FILED MAR.2, 1921.

1,397,785. Patented Nov. 22, 1921.

. j g; ,1 1 F n 1,2 111mm [m gwuenfo'a 41 0; Z6 Ewe c7?! material whichmay and which will compare favorably in PATENT OFFICE.

GEORGE U. BOSE, JR., OF WASHINGTON, DISTRICT OF COLUMBIA.

ELECTROTYPE MATERIAL AND METHOD \OF FORMING SAiME.

' To all whom it may concern:

Be it known that I, GEORGE U.Rosn, Jr., a citizen of the United Statesof America, residing at Washington, in the District of Columbia, haveinvented certain new and useful Improvements in Electrot pe Material andMethods of Forming ame, of which the following is a specification.

w'ldy present invention relates. generally to electrotype materials andmore particularly to materials from which printing plates are made, myobject bein the provision of a be electro deposited strength anddurability with the hardened .steel plates now used, a well as a methodby which the electrotype material may be strengthened for this purposeduring the electro-deposition thereof.

llt is a well known fact that printing plates are at the present timeformed by what is known as the transfer process, each plate being madefrom a roller which has previously received its impression from a masterplate or die. Each printing plate must be so fashioned from a roller andthen I hardened before use and the process, in-

volving as it does, considerable hand work and skill, is both expensiveand time consuming to such an extent that plates cannot now be finishedin the required number.

The electro-depositing process of forming printing plates is known andused to a certain extentand according to this process a previouslytransferred plate is used-for the electro-deposition of a positive plateknown v as an alto, by the subsequent use of which any desired number ofnegative printing plates may be formed by electro-deposition. Theseprinting plates are known as bassos and it is evident that this process,in which copper is universally employed, ipvolves but a single transferoperation and can, be

tively few impressions are to be made, for

a plate formed by the electro-deposfition of copper is not ofsufiicientstrength to permit of its use for the printing of bank notesand the like where impressions are to be Specification of LettersPatent. Patented NOV. 22, 1921.

Continuation of application Serial No. 366,463, filed March 17, 1920.

Serial No. 449,273.

This application filed March 2,

made in great numbers. In other words .an electro-deposited copper platedoes not compare favorably from an economical standpoint with a hardenedsteel plate which can only be made by the transfer process.

My invention aims to permit the formation by electro-deposition of aplate which Wlll compare favorably in strength with hardened steel andwill thus beof great advantage, and arises from a discovery that theweakness of electro-deposited copper is due to the greatly increasingcrystals formed in the metal as the depos1t thickens. I have found thatthe operation starts with the deposit of dense fine grains which if.continuedwould produce a strong material. As the deposited metalincreases in thickness however, the crystals grow to great proportionsand form what are known as trees thus weakening the structure andcausing a rough deposit which necessitates considerable and expensivemachinery in smoothing the edges'and back of the plate.

According to my invention, as shown in the accompanying drawing whereinthe figure is a cross-section through the material thereof, the methodis varied to the extent that the copper is electro-deposited in separatelayers 10 to the full thickness of the material and in such manner thateach new layer breaks up the growth of the crystals and thus interruptstreeing to such an extent that it is practically the start of an entirenew operation. This maybe accomplished by electro-depositing certainlayers in a sulfate solution and alternate layer in a cyanid solution,but I do not limit myself to such an operation as the same result mightbe accomplished in a single solution by periodically varying the densityof the electric current utilized.

Ihave also found that by 'interposi-ng between copper layers, a layer ofa diiferent material instead of layers of the same material of differentcrystalline structure, pro nouncedly better results can he obtained.

For instance layers 11 of nickel can be electro-deposited between layersof copper and not only check the growth of copper crystals thuspreventing excessive treeing, but add to the tensile strength of thefinished product by virtue of the relatively greater strength of thenickel.

Where, as shown in the drawing, nickel layer 10 are utilized betweenlayers 11 of copper, the deposits of nickel will be greatly reduced inthickness as compared to the layers of copper as it is the frequencyably in strength and durability with hardened steel as I havedemonstrated by actual use, and which will, by virtue of the materialchecking of the growth of the crystals, obviate much of the expensivemachining 'now necessary with electro-deposited plates wherein copper ofa given crystalline structure is utilized in one continuous operation. v

It is to be understood that in speaking of the electro-deposition ofeither copper or nickel, I refer to the ordinary well known operationsof this nature, employing generally the solutions usually employed, andusing generally a current density variable within the limits nowprescribed, and while my invention is capable of being readily carriedout by any one skilled in the art of electro-deposition, I do not wishto be understood as limiting myself to the ordinary process of electro-.depositing copper and nickel, even though these will serve thepurpose. For convenience and better understanding I will give theoperation as carried out to produce a plate of alternating layers of coper and nickel, as follows. After thorough y cleaning a master orengraved plate, from which an alto is to be made forsubsequent use inthe electrodeposition of any desired number of .bassos, isfirstsuspended in a nickel solution of nickel sulfate, nickel chloridand boric acid, and nickel deposited at a current'density of about 10amp/sq. ft., for about ten minutes. Then at a current den- 'sity ofabout 20- amp. /sq. ft., the deposition is continued for the balance ofan hour the initial deposit of nickel therefor being about .001 inch forthe alto. The plateis then withdrawn, rinsed and immersed in acoppersolution of copper sulfate and sulfuric ac d and deposition proceededwith at a -current density between 35 and 45 amp/sq. ft.

for about two hours so as to produce a cop-'- per layer on the nickellayer of about .0045

inch in thickness. The plate is then with-- drawn from the coppersolution, rinsed and again immersed in a nickel solution and.

nickel deposited at about 20 amp/sq. ftflfor one hour. This cycle of twohours in copper and one hour in nickel is repeated until the requiredthickness of the plate is obtained} When this has been reached, with anallowance for waste, the. plate is removed and machine, the altoseparated from the master plate and then utilized in a similar manner inthe formation of any number of bassos, the formation of each of which iscarried out in a similar process except that the initial deposit ofnickel will be somewhat thicken for bassos than for altos, being forinstance about .002 inch.

It is also to be understood that the current densities mentioned aboveare given by way of illustration alone and that I reserve to myself theright to vary the same at will.

It is not to be assumed, however that the material and method of formingthe same as proposed by my invention, is useful alone in connection withrinting plates, for it is obvious it will find wide, in fact more orless eneral use, in various arts where electroeposition, can beeffectively utilized in place of diflicult casting operations. 1

I am aware it is not new to electro-plate articles with alternate layersof copper and nickel where the purpose is to support and hold thenickel, but such a method is foreign to the present one, in fact it isthe reverse of my invention which seeks to provlde an independentelectro-deposited material for the most part, .at least, of copper, andof a greater tensile strength than a material formed wholly of copper ofa given crystalline structure in a continuous operation,

such as to enable it to com are favorably in strenth and durability toardened steel.

I claim:

1. The herein described method for the electro-deposition of copper to athickness usually forming trees and producing little tensile strength,which consists in electrodepositing the copper in a number of layers andin breaking up the growth of upper crystals between the layers wherebyto check the formation of trees and correspondingly increase strength ofthe finished plate.

2. The herein described method for the electro-deposition of a materialsubject to treeing 'in thick deposits, which consists inelectro-depositing the material in relatively thin layers to the desiredthickness and in breaking up the growth of crystals between the layers,whereby to check the formation of trees and increase the strength of thefinished product.

'3. he herein described method of electro:

depositing a material subject to" treeingZ in thick deposits whichconsists in depositing a relatively thin layer of such material, then.

depositing on the first 1a er a second layer of a material having-afi'erent crystalline structure, and then alternating-these deposits tothe desired thickness, whereby no check treeing, and increase tensilestrength.

4. The herein described method of forma ing an independently usablematerial, which consists in successively.electro-depositing a pluralityof adhering layers of the same material and in inter-depositing betweenlayers of the material, other layers having a different crystallinestructure.

5. The herein described method of forming an independently usablematerial which consists-in successivel electrordepositing a plurality ofadhering layers of the same material and in inter-depositing betweenlayers of the material, layers of another material.

6. The herein described step in the method of strengthening electrotypessubject to tre'eing during the electro-deposition thereof, whichconsists in periodically checking the growth of crystals in order toavoi treemg, as described. a 4

7 The herein described step in the method of strengthening electrotypessubject to treeing during the electro-deposition thereof, which consistsin periodically interrupting the normal operation and checking thegrowth of or stals at each interruption in order to avoi treeing.

8; The herein described method of forming electro-deposited copperplates which consists in depositing copper in separate layers and ininterdeposi-ting relatively thin layers of nickel between the layers ofthe copper as-described'. .w j

9. The herein described method of forming electro-deposited materialwhich consists in depositing copper in separate layers and ininterdepositing relatively thin layers of nickel at frequent intervalslayers of copper as described.

10. An electro deposited material consisting of alternate thin layers ofnickel and thick layers of copper. 7

11'. An electro-deposited material consist: ing of alternate layers of.copper and nickel, the layers of nickel being relatively thin ascompared to the layers of copper and lo-' between the cat/ed at frequentintervals throughout the formedcof a pluralityof alternating layers.

of copper and nickel as and for the purpose v set forth.

In testimony whereof I have afiixed my

